Example embodiments disclosed herein relate to variable resistance memory devices, for example, to variable resistance memory devices reducing an area of a Y-pass driver.
Semiconductor memory devices are memory device that can store data and readout the stored data when necessary. Semiconductor devices may be classified into random access memory (RAM) devices and read only memory (ROM) devices. ROM devices are nonvolatile memory device that retain their stored data even when their power supplies are interrupted. ROM devices may include a programmable read only memory (PROM), an erasable programmable read only memory (EPROM), an electrically erasable programmable read only memory (EPROM) and a flash memory. A flash memory may be divided into a NOR flash memory and/or a NAND flash memory. RAM devices are volatile memory devices that lose their stored data when their power supplies are interrupted. RAM devices may include a dynamic random access memory (DRAM) and/or a static random access memory (SRAM).
Semiconductor memory device substituting a nonvolatile material for a capacitor of DRAM have been introduced. For example, there are a ferroelectric RAM (FRAM) using a ferroelectric capacitor, a magnetic RAM (MRAM) using a tunneling magneto-resistive layer and a phase change memory device using chalcogenide alloys. The phase change memory device is a nonvolatile memory device using a phase change (e.g., a resistance change) according to a temperature change. A manufacturing process of a phase change memory device may be relatively simple and therefore a large quantity of memory may be produced at a relatively lower cost.
A phase change memory device may include a write driver circuit to supply a program current to a phase change material (GST) when a program operation is performed. The write driver circuit may supply a program current (e.g., a set current or a reset current) to a memory cell using a supply voltage higher than 2.5V externally provided. Here, the set current may be a current for making a phase change material (GST) of a memory cell a set state and the reset current may be a current for making a phase change material (GST) of a memory cell a reset state.